The use of optical devices in various applications has brought about a need for the capability of coupling optical devices together in situations where the applicable light source from the incoming optical device is already energized, creating a risk that damaging light will endanger those exposed to it. For example, various systems and devices used for medical purposes incorporate the use of an optical source (for example, a laser) for a variety of applications, including utilizing light to visually determine the location of certain medical devices as they travel through a patient's body. The optical source can be something in the visible spectrum (i.e., can be seen with the naked eye) or something in the non-visable spectrum that may require the use of additional apparatus to view the light source at issue.
An example of one application of this technology incorporates a catheter stylet with an optical fiber that allows the medical provider to correctly position the catheter within the patient. Other applications include the use of fiber optic technology to facilitate the medical use of laser catheters to ablate lesions or perform angioplasty. As the technology develops, it is expected that the use of optical devices in conjunction with various light sources will greatly increase in the medical industry.
However, various light sources used in such applications (e.g., light emitting diodes, lasers, etc.) can be harmful to those who may be exposed to the light eminating from the source. Damaging light can be produced from a variety of sources and can injure a person, such as causing damage to eyesight (e.g., retina, lens). For example, the coherence and low divergence of laser light means that it can be focused by the eye into an extremely small spot on the retina, quickly (sometimes in less than one second) resulting in localized burning and permanent damage.
Various standards apply to the safety of laser products emitting laser radiation and have led to the adoption of safety designations. Lasers have been classified according to the degree of optical radiation hazard in order to aid hazard evaluation and to adequately develop user safety control measures. Lasers are usually labeled with a safety class number that identifies how dangerous the laser is. Class I lasers are inherently safe as the light is either low power or very diffuse. Class II lasers are considered safe during normal use as the blink reflex of the eye will generally prevent damage. Lasers of Class III and above present increasing levels of risk for significant damage of both eyes and skin.
People working with Class III and above can protect their eyes with safety goggles that are designed to absorb light of a particular wavelength. Such precautions and perhaps other protective gear would normally be required in systems where optical connectors are coupled to other connectors outside of an enclosure. In certain medical applications, for example, one optical device provides the light source of the system, while the second optical device connector is a disposable component of the system that is changed out and discarded after each use cycle of the system (e.g., catheter stylets with optical fibers).
Regulations or product guidelines may explicitly require that the light source transmitted from the source optical device be turned off when the disposable component of the system is changed out for lasers classified as Class III or above. Alternatively, protective gear may be required for any system operator or other person whose eyesight could potentially be exposed to the damaging light. However, the danger that system operators will not power down the light source when appropriate or fail to use suitable protective gear (or fail to use it properly) in the operation of the system is high. Also, problems could exist where the coupling between the light source and the target connector fails (sometimes because of a failure to properly interlock the connectors, and sometimes because of mechanical failure). Such a failure could result in damage to operators and patients.